I did manage to read Butler's Xenogenesis twice, but I think my ability to appreciate it was damaged by inadvertently reading #2 in the trilogy first (I got confused figuring out which book was first) and doing so when I was in middle school before I had any clear idea what sex was, which made large portions of the plot completely incomprehensible. :/ The second time did go better but there's something about the way I first encounter a work that influences future readings.

Certainly, there is sport to be had in challenging someone who claims to have read all the classics by inquiring if they have read anything by well-known authors who happen to fall into a particular category.

Sure, depending on where you draw the line chronologically. Although I wouldn't agree with them, I could certainly see someone drawing the line at to exclude "That New Wave Stuff" and classing anything John W. Campbell wouldn't have bought as not being "Classic" and that would absolutely exclude the authors you mentioned.

Similarly, I could see some of the surly sexist curmudgeons out there coming up with rules to allow in later work by manly-men SF writers, while finding a way to rule out anything with too many girl cooties on it.

On a slightly different subject though, just how much would you have to have read by a particular author to be considered "familiar" with them? I've read a handful of works by all three authors (I own single author antholigies by each of them, and have read other of their works in multi-author antholigies, and I might have read a novel or two.) you've mentioned and I've also read a fair amount *about* the authors. I'd be inclined to say that I'm "familiar" with them and their work, but I wouldn't say I've read them extensively.